The European Central Bank (ECB) should create a central database of all its corporate bond purchases in order to allay concerns that its programme could favour specific companies, according to Fine Gael MEP Brian Hayes.
In the past year, six European Union central banks, co-ordinated under the ECB's Corporate Sector Purchase Programme (CSPP), have bought a total of €89bn in corporate bonds.
The CSPP is designed to help bring inflation in the region back to about 2pc, as well as help businesses across Europe enjoy better access to credit.
Ryanair, Kerry Group and CRH are among those to have participated in the programme.
Mr Hayes is one of a number of MEPs who have called for greater transparency in the CSPP.
"The level of transparency for this programme is very low," claimed Mr Hayes.
"(ECB) President (Mario) Draghi says that it is up to national central banks to publish the information about the bond purchases. Unfortunately, many national central banks do not provide enough information on the bond purchases."
Some bond experts have recently been reported as saying that introducing greater transparency could result in unwelcome distortions in the bond market.